Benthic Comb Jelly

A new species of benthic comb jelly found at the depth of 7217m in the Ryukyu Trench off of Japan takes the record for deepest living ctenophore.

Literally hanging, or rather flying, by a thread, a new species of comb jelly, or ctenophore, has been found living at depths deeper than that of any ctenophore previously known to science. This unique species, which flies like a kite on the end of two long "strings" attached to the sea floor, has been observed at the bottom of the Ryukyu Trench and is thus raising questions about the availability of food resources at that depth. Previously, it was thought that the abyssal depths of deep sea trenches such as this one could not support predators that rely on macroscopic food sources, but are sessile and do not actively hunt. The presence of this abyssal, benthic comb jelly suggests that there are missing pieces of the story of life in this environment.

Observed by the ROV Kaiko on a dive into the Ryukyu Trench in April 2002, the video and images of this unique bottom dwelling ctenophore remained "undiscovered" until several years later. In April of 2006, scientists on a Census of Marine Zooplankton (CMarZ), a field project of the global Census of Marine Life, research cruise to the Sargasso Sea aboard the R/V Ronald H. Brown observed a number of rare deep-sea ctenophores. Their observations led to the re-examination of cydippid ctenophore taxonomy and ,eventually, to the suggestion of two new families of cydippid ctenophore. Due to several taxonomic affinities, researchers studied this species for inclusion in the genus Aulacoctena. However, this probing revealed not only that this specimen did not warrant inclusion into Aulacoctena, but also that Aulacoctena likely belongs in a new family, which researchers have tentatively named Aulacoctenidae. Further, the researchers believe that a second new family will have to be erected to contain this new species.

Researchers worldwide are striving to understand the species compositions, ecological processes, and related environmental mechanisms associated with deep ocean trenches. As in this case, our understanding of these subjects becomes more complete with each new species or finding. With the ocean trenches being among the last remaining frontiers on earth, it is likely that many new forms of life may yet be discovered in their depths.

What: Discovery of a new species of abyssal, benthic comb jelly in the Ryukyu Trench, Japan